How are Roman law, the Justinian Code, and the Napoleonic Code related?

The Napoleonic Code established a single written and also accessible law which replaced some previous patchwork of feudal laws and ended up creating a modern code.

The Justinian Code was just a collection of some edited extracts from the centuries of Roman laws.

The Napoleonic Code established a single written and accessible law which replaced previous patchwork of feudal laws and created a modern code. It ignored previous French legal frameworks and used the Corpus Juris Civilis, also known as Justinian Code, as its inspiration. However, the Napoleonic code was different. The Justinian Code was a collection of edited extracts from centuries of Roman laws. The Napoleonic code was a complete rewriting of the law which was put together in a more systematic and rational way. It also incorporated some previous French rules.